Radio apparatus



June 29, 1937. 1 M. PERKINS RADIO APPARATUS v Filed April 3, 1931 I f2 A? I 30 l /7 U//U/ i7 0 I A /4 I I I I 22 I f f Z0 I l I z I I I /6 Q i O I I /8 I I l 05+ I L-/Uf' i l I' I T T Imm Jdurence 7??. per-hns Patented June 29, 1937 RADIO APPARATUS Laurence M. Perkins, Dayton, Ohio, assignor, by mesne assignments, to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application April 3, 1931, Serial No. 527,473

12 Claims.

This invention relates to a radio apparatus and more particularly to a system for coupling stages. It is a common practice to couple stages either by condensers or transformers. When condensers are used it is customary to use fixed condensers having a pair of plates. This is found to be objectionable in production, in that the condensers are expensive and are diflicult to mount. Transformers using an air core are cheaper but the results are not as desirable, in that, the gain is not as uniform throughout the frequency range.

-An object of the present invention is to use the equivalent of a condenser coupling without the use of the conventional xed plate condenser. This has been accomplished by connecting the output circuitl of one tube to the input circuit of the succeeding tube by a single turn open circuited coil that is connected by a conductor to one of said circuits and electrically associated with an inductance of the other circuit so that the output signal of one tube is transmitted to the input of the other.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawing:

Fig. 1 discloses a schematic diagram of a portion of a radio apparatus employing the invention.

In the drawing the output circuit including the anode I4, the inductance I6, the condenser I8 and the cathode 2l] of the tube Ill is coupled to the input circuit including the grid 22, the resonant circuit comprising the condenser 2li, and the inductance 26 and the cathode 28 of the tube I2 by a single turn or loop open circuited coil 30.

In the preferred modification as disclosed, a single turn coil 30 is Wound adjacent to, either over or to one end of, the inductance 26 and is connected to the anode circuit of the tube I by a conductor 32. The coil 36, which has one end open circuited, is electrostatically connected to the inductance 26. The inductances I6 and 26 are magnetically segregated as indicated by the dashed line between said inductances. If the single turn open circuit coil 30 is wound over the inductance 26, this inductance acts as an autotransformer that has a winding tapped where the coil 30 is located.

Although a single turn open circuited coil has been disclosed, it is understood that instead of a single turn only a fraction of a turn may be used or certain cases may justify the use of several turns depending entirely upon the design of the circuits and the frequency range of the signals. In the present modification, tuned radio frequency amplication stages have been disclosed. However, the invention is not limited to radio frequency, in that, it may be used for coupling a radio frequency amplifier to a detector or it may be used in coupling stages amplifying the intermediate frequency of a superheterodyne receiver or any other place where ultra audio signal currents are used.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A coupling system for electrically connecting one stage of radio frequency amplification to a succeeding stage, each stage having a control electrode circuit and an anode circuit, and each of said circuits including an inductance, the combination comprising, an open circuited conductor having at least one complete turn connected to one of said inductances and mounted so as to be spaced near' one end of another 0f said inductances, said conductor and the end turn of the inductance that the conductor is spaced from forming a condenser, the capacity of which determines the coupling between said inductances.

2. A coupling system for coupling magnetically segregated inductances, comprising in combination, an open circuited conductor having one or more complete turns connected to one end of one of said inductances and electrostatically coupled to the total end turn of another inductance, and means including the length of said conductor and space between said conductor and said end turn for determining the coupling between said inductances.

3. A coupling system for coupling magnetically segregated inductances, comprising in combination, a conductive element having more than one complete turn, means connecting said element to one end of one of said inductances, electrostatic coupling between said element and an end turn of another inductance, the physical dimensions of said conductor and space between said conductor and said end turn being major factors in determining the coupling between said inductances.

4. A system for coupling radio frequency stages having an inductance in the output circuit of one stage magnetically segregated from an inductance in the input circuit of a succeeding stage,

comprising in combination, an open circuited conductor having a plurality of turns connected yto one end of one of said inductances and coupled to one end of the other of said inductances, and means including the length of said conductor and space between said conductor and the end of the inductance to which said conductor is coupled for determining the coupling between said stages.

5. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil in the grid circuit, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to a point the potential of which varies during the operation of the system, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

6. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil, variations in voltage in which produce corresponding variations in grid potential, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to a point the potential of Which varies during the operation of the system, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

7. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil in the grid circuit, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to a point of varying potential extraneous to the grid circuit, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

8. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil, variations in voltage in which produce corresponding variations in grid potential,

and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to a point of varying potential extraneous to the grid circuit, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

9. An amplifying system including a thermionic tube having cathode, grid and plate elements, a tuned grid circuit joining the grid and cathode of the tube and including a coil and condenser, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to a point the potential of which varies during the operation of the system, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

l0. An amplifying system including a plurality of thermionic tubes each of which has cathode, grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, a coil, variations in voltage in which produce corresponding variations in the potential of the grid of the succeeding tube, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to said plate circuit, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

11. An amplifying system including a plurality of thermionic tubes each of which has cathode, grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, a coil, variations in voltage in Which produce corresponding variations in the potential of the grid of the succeeding tube, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected to the plate of the preceding tube so as to be at substantially the same potential as the plate, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

12. An amplifying system including a plurality of thermionic tubes each of which has cathode, grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, a coil, variations in voltage in which produce corresponding variations in the potential of the grid of the succeeding tube, and a conducting member spaced from, but closely adjacent to, convolutions of the coil, said member being connected so that variations in potential are produced therein corresponding to variations in potential of the plate of the preceding tube, the capacity between the member and coil providing a low coupling impedance at radio frequencies.

LAURENCE M. PERKINS. 

